Transportation was a huge culture shock for many of us when we first arrived in Spain. Personally, whenever I need to go somewhere, whether it be a grocery store, the movies, a bar, I drive my car. I can leave when I want and get where I am going in five minutes. Then when I am ready to go home, I can drive back whenever I please. However, with public transportation, I had to learn to be more patient and flexible.
One has two options. Either memorize the train/metro schedule and let it determine your schedule for the day. Or just go with the flow and be patient when there may be long waiting times between trains.
On the bright side, it provides a great opportunity to people watch the locals. Locals are not afraid to stare at you for long periods of time. If Americans are caught staring, they usually glance away sheepishly. In addition, Americans tend to be more rambunctious on the train than locals. The train ride for locals is a time to catch a quick nap or read the newspaper. Finally, Americans can be spotted from a distance when they often kick their feet up on the seat to relax.
When I return to the States, I will definitely miss all the fun activities that happened on the metro but it will also be nice to be able to drive my own car and get places faster.